The invention relates to the field of systems for measuring the location of the center of gravity of an aircraft while in flight and in particular to such systems utilizing inertial components.
There are a number of reasons why it is considered desirable to be able to locate the exact center of gravity of an aircraft in flight including safety considerations. For example, the location of the center of gravity affects the control stability of the aircraft. In addition, the position of the center of gravity in the aircraft can be related to fuel consumption since the performance of the aircraft is affected by the attitude and the trim of the aircraft. In the case of a fixed wing aircraft, for instance, it is often possible to save fuel by moving the center of gravity aft which reduces the required stabilizer down load and hence drag.
An accurate knowledge of the center of gravity of the aircraft, in addition to permitting the crew to accurately assess the control and stability margins of the aircraft, will permit the crew or an automatic system to make the appropriate adjustments in the location of the center of gravity, by, for example, pumping fuel from one tank to another, in order to permit trimming of the aircraft for optimum performance.
One approach for determining in-flight center of gravity is to locate the center of gravity of the aircraft while it is on the ground either by calculating the center of gravity by utilizing the weight and location of passengers, cargo, and fuel loaded on the aircraft or by using an automatic weight and balance system such as the system disclosed in Bateman U.S. Pat. No. 4,312,042. Then the location and amount of fuel burned is audited to update the location of the center of gravity while in flight. However, these types of systems are subject to significant errors arising out of inaccuracies in fuel burn computations and shifts in passenger and cargo locations as well as errors that may be present in the initial measurement of the center of gravity on the ground.